quench the remaining NHS group on the slide H from Schott

Many researchers had quenched the remaining NHS group on the slide H from schott with 50mM ethanolamine in sodium borate (pH9.2)for 1 h at room temperature. I repeated this procedure many times. However, the results were frustrated.

Any tips existed in this process, such as shaking? I look forward to more details of this quenching method.

By the way, the printed slides were put in the vacuun drying chamber at 37℃ for 16h to immobilze the peptides in my experiments. Would this step affect the subsequently blocking?